The present invention relates to a filling apparatus for, a filling system for and a method of introducing into a container a suspension or solution of a substance, in particular a pharmaceutical substance, in a propellant under pressure. Most particularly, the present invention relates to a filling head included in a line in which a propellant under pressure containing a substance in a suspension or solution is circulated, with the filling head being brought into and out of communication with containers to be filled.
Containers for holding a suspension or solution of a pharmaceutical substance in a propellant under pressure are well known. One such known container comprises a body which defines a storage chamber, a valve stem which extends from a head of the body and a metering chamber which is selectively communicatable by the valve stem with the atmosphere and the storage chamber; the valve stem providing, via an L-shaped conduit which extends between the free end and the side wall thereof, the outlet of the container through which metered doses of propellant containing pharmaceutical substance are delivered. The valve stem is axially displaceable between a first, extended position in which the metering chamber, and hence the container, is closed to the atmosphere since the L-shaped conduit is disposed wholly outside the metering chamber, and a second, depressed position, in which the metering chamber is in communication with the outlet provided by the L-shaped conduit in the valve stem and through which a metered dose of propellant containing pharmaceutical substance is delivered. The container is filled with the valve stem in the depressed position, with the propellant containing pharmaceutical substance being forced downwardly through the L-shaped conduit in the valve stem, through the metering chamber and into the storage chamber defined by the body of the container.
EP-A-0419261 discloses a filling system for introducing into a container a suspension or solution of a pharmaceutical substance in a propellant under pressure, which filling system includes a filling apparatus that prevents the escape of pharmaceutical substance into the atmosphere. In this filling system the filling apparatus is configured to be flushed by a volume of high pressure propellant while still in fluid communication with the container so that the propellant under pressure containing pharmaceutical substance which is remaining in the filling apparatus after filling the container with the same is flushed through into the container prior to withdrawal of the filling apparatus from the container. This configuration does, however, require additional propellant to be introduced into the container to achieve the flush. Moreover, following the flushing action, propellant under pressure present in the valve stem can escape to the atmosphere.
The present invention in at least one preferred aspect aims to provide an improved filling apparatus which at least partially overcomes the above-mentioned problems.
The present invention also aims to provide a method and filling system which are configured to fill a container without requiring the release of propellant alone or propellant containing pharmaceutical substance directly to the atmosphere.
The present invention provides a filling apparatus for introducing into a container a suspension or solution of a substance, in particular a pharmaceutical substance, in a propellant under pressure, comprising: a main body including a passageway for communicating, in use, with a valve stem extending from a head of a body of a container, the container comprising a metering chamber selectively communicatable by the valve stem with the atmosphere and a storage chamber defined by the body; a fill actuator comprising a filling valve assembly in communication with the passageway for selectively introducing thereinto propellant under pressure containing a substance in a suspension or solution; an exhaust actuator comprising an exhaust valve assembly in communication with the passageway for selectively exhausting therefrom propellant under pressure containing substance; and a container-engaging body in communication with the passageway for receiving, in use, the head of the body of the container, the container-engaging body being movable relative to the main body so as thereby to cause the valve stem of the container to be selectively positioned in an extended closed position, a depressed open position or an intermediate position therebetween, in which intermediate position the metering chamber of the container is closed to the atmosphere.
Preferably, the filling apparatus further comprises biasing means for biasing the container-engaging body away from the main body.
More preferably, the biasing means comprises at least one compression spring disposed between the main body and the container-engaging body.
Preferably, the main body includes an outwardly-extending part through which the passageway extends and which is sealingly received within a bore in the container-engaging body.
More preferably, the filling apparatus further comprises an annular seal disposed at the distal end of the outwardly-extending part of the main body, which seal is, in use, abutted by the distal end of the valve stem of the container.
Preferably, the container-engaging body includes a chamber of greater radial dimension than the valve stem of the container into which, in use, extends the valve stem of the container and a conduit in communication with the chamber for feeding a pressurised fluid thereto.
Preferably, the container-engaging body includes an annular seal disposed about a lower end of the chamber against which, in use, is abutted the head of the body of the container which surrounds the valve stem thereof. More preferably, the annular seal comprises an O-ring.
Preferably, opposing surfaces of the main body and the container-engaging body include one or the other of at least one projection and at least one recess, whereby, when the main body and the container-engaging body are moved together, the at least one projection is engaged within the at least one recess.
The present invention also extends to a filling system for introducing into a container a suspension or solution of a substance, in particular a pharmaceutical substance, in a propellant under pressure incorporating the above-described filling apparatus.
The present invention further provides a method of introducing into a container a suspension or solution of a substance, in particular a pharmaceutical substance, in a propellant under pressure, comprising the steps of: providing a container comprising a body defining a storage chamber, a valve stem extending from a head of the body and a metering chamber selectively communicatable by the valve stem with the atmosphere and the storage chamber, the valve stem having an outlet opening and a inlet opening and being movable between an extended closed position in which the inlet opening is located outside the body and a depressed open position in which the inlet opening is located within the body; communicating the outlet opening of the valve stem of the container with a passageway in a main body of a filling apparatus, the filling apparatus comprising a fill actuator comprising a filling valve assembly for selectively introducing into the passageway propellant under pressure containing a substance, in particular a pharmaceutical substance, in a suspension or solution and an exhaust actuator comprising an exhaust valve assembly for selectively exhausting from the passageway propellant under pressure containing substance; depressing the valve stem of the container so as to provide a communication path to the storage chamber thereof; opening the filling valve assembly thereby to fill the storage chamber of the container with propellant under pressure containing a substance, in particular a pharmaceutical substance, in a suspension or solution; closing the filling valve assembly; moving the valve stem of the container to an intermediate position between the depressed open position and the extended closed position, in which intermediate position the metering chamber of the container is closed to the atmosphere and the inlet opening in the valve stem of the container is located outside the body thereof; and opening the exhaust valve assembly to enable propellant under pressure containing substance in the passageway and the valve stem of the container to exhaust.
Preferably, the filling apparatus further comprises a container-engaging body which is movably disposed to the main body thereof and is configured to receive the head of the body of the container which includes the valve stem, and the method further comprises the step of biasing the container-engaging body away from the main body of the filling apparatus.
More preferably, the main body of the filling apparatus includes an outwardly-extending part through which the passageway extends and which is sealingly received within a bore in the container-engaging body.
Still more preferably, the method further comprises the step of sealing the distal end of the outwardly-extending part of the main body against the distal end of the valve stem of the container.
Preferably, the method further comprises the step of surrounding the part of the valve stem of the container which includes the inlet opening and extends from the body of the container with a pressurised fluid at least when the exhaust valve assembly is opened to exhaust propellant under pressure containing substance from the passageway and the valve stem of the container.
Preferably, the pressurised fluid is at a pressure greater than the vapour pressure of the propellant under pressure containing substance.
In a preferred embodiment the fluid is a gas. Preferably, the gas is one of air or nitrogen.